Prenatal exposure to alcohol can result in a variety of morphological and behavioral abnormalities in humans. However, there are wide variations in outcome given similar alcohol exposure histories and it has been proposed that differential tolerance to ethanol might be one reason for this variation. Therefore, one aim of the current proposal is to determine if the degree of tolerance to ethanol influences the severity of alcohol's effects. Rat pups from two selectively bred lines the P and NP lines, will be studied for their susceptibility to the effects of alcohol exposure. While these lines were bred for extremes in alcohol preference they also differ in their development of tolerance to ethanol. These two lines and Sprague-Dawley rats will be exposed to ethanol during a period of rapid brain growth, while ensuring adequate nutrition. Rats exposed to ethanol using this procedure show a variety of central nervous system anomalies and a limited number of studies suggest that behavior may be particularly affected by exposure during this period. Data also indicate that many of the behavioral problems seen in children exposed to alcohol in utero are more severe if the mother drinks throughout her pregnancy than if she stops drinking prior to the third trimester, when the brain growth spurt occurs. Thus in addition to looking at the role differential tolerance may play in alcohol's teratogenic effects, we will further characterize behavioral dysfunctions associated with ethanol exposure during this period and determine the permanence of such effects.